Embodiments relate to a semiconductor device and a method for manufacturing the same, and more particularly to a semiconductor device in which a seam formed in a device isolation film defining an active region is filled with a sacrificial film, and a method for manufacturing the same.
With an increasing integration degree of a semiconductor device, a pattern, including a device isolation region, formed over a cell region of a semiconductor substrate has been reduced to prevent the occurrence of electric connection between patterns.
A conventional device isolation region has been formed through a local oxidation of silicon (LOCOS) process. As the device isolation region has been gradually reduced in size, a shallow trench isolation (STI) process capable of forming a superior small-sized device isolation region has been developed as an alternative to the LOCOS process.
In accordance with the STI process, after a trench having a predetermined depth is formed in a semiconductor substrate, an insulation material is deposited to fill the trench, and an unnecessary insulation film is removed through a subsequent CMP process, such that a device isolation region for electrically isolating active regions is formed.
However, as a design rule is gradually reduced, an aspect ratio of a trench is gradually increased, such that a method for forming a device isolation film using the STI process is confronted with the limitation in trench filling.
For example, a void or seam may occur in an insulation film when the insulation film is filled in the trench, such that reliability and productivity of a highly-integrated semiconductor device are reduced. If the seam occurs in a device isolation film, a word-line material may extend into the seam when the word line (gate) is formed in a subsequent process, resulting in a bridge between several word lines.
Moreover, when the device isolation film is formed of an oxide film so as to minimize the loss of a silicon substrate as well as to maximize a thickness of a wall oxide film, seams (or voids) may occur in the device isolation film.